1. Field of the Invention
This invention pertains generally to devices for closing off the opening of the fireplace to inhibit the drawing of air therein.
2. Description of the Prior Art
It is well known that the updraft resulting from hot gases arising from a fire in a fireplace will draw out large amounts of heated air out of a room and discharge this heated air through the chimney. Glass doors are commonly utilized to close off the fireplace opening where an external source of outside air can be introduced into the fireplace to maintain combustion. Such glass doors allow radiated heat to enter the room, but prevent room air from entering the fireplace. Glass doors may be utilized in fireplaces not having an outside source of ventilation air, but in such a case a closeable ventilator must be provided in the glass door enclosure to allow some room air to be drawn into the fireplace to maintain combustion.
Where the use of the above described fireplace doors is not possible, or is not desired for aesthetic reasons, substantial amounts of room heat can be lost through the fireplace. During active combustion of the fire in the fireplace, this room air loss is generally compensated for by the heat conducted and radiated from the fire itself, and it would obviously not be desirable to close off the fireplace opening during the time the material is burning in the fireplace. After the material in the fireplace has completely died down, the damper on the fireplace chimney may be closed to prevent loss of room heat through the chimney. However, during the period of time that the fire has substantially died down but is continuing to smolder, the damper cannot be closed without introducing smoke into the room, and it is during this period of time that substantial amounts of room heat are lost through the fireplace without any compensating gain of heat from combustion in the fireplace. Moreover, in older fireplaces the damper system often does not provide an adequate seal, and a considerable amount of warm room air is able to rise through the fireplace.
To prevent the loss of heated air through the fireplace when active combustion is not taking place therein, various closure devices have been proposed to temporarily seal off the opening of the fireplace. Various of these devices employ a window shade type device mounted above the fireplace opening, in which a fire resistant fabric is pulled down in the manner of a window shade to cover the fireplace opening. An example of this type of device is shown in the U.S. patent to Luther, U.S. Pat. No. 3,375,818. Such devices require a permanent mounting above the fireplace, and thus detract from the appearance of the fireplace, and they do not adequately close off the sides of the fireplace opening as air is sucked into the fireplace opening by the updraft from burning embers.